Valve



June H, 1963 R. B. JOHNSTON 3,093,152

VALVE Original Filed Sept. 23, 1957 3 Sheets-Sheet 1 .fi r 2 fiufua E.dob/w fan INVENTOR.

ATTORNEYS June 11, 1963 R. B. JOHNSTON 3,093,152

VALVE Original Filed Sept. 23, 1957 3 Sheets-Sheet 3 Rufus .5. dofinsfonINVENTOR.

BY I M ATTORNEYJ United States Patent 3,093,152 VALVE Rufus B. Johnston,Dallas, Tern, assignor to Wilson Srupply Company, Houston, Tex., acorporation of exas Original application Sept, 23, 1957, Ser. No.685,583, now Patent No. 2,914,037, dated Nov. 24, 1959. Divided and thisapplication Apr. 14, 1959, Ser. No. 806,303 7 Claims. (Cl. 137-87) Thisinvention relates generally to valves and, more particularly, to animproved reversing valve of the type shown in my copending applicationfiled or even date herewith and entitled Valve, which application is adivision of my copending application, Serial No. 577,435, filed April10, 1956, now patent number 2,914,036 dated November 24, 1959, andentitled Hydraulic Pumping System.

The present application is a division of my depending application,Serial No. 685,583, filed September 23, 1957, now patent number2,914,037 dated November 24, 1959, :and entitled Improved HydraulicPumping System.

As pointed out in the afiorementioned copending applications, motors ofthis general type customarily include a pilot valve control so connectedto the motor cylinder as to automatically and positively sh-ifit areversing valve between positions for admitting and exhausting hydraulicfluid to and from the working side of the motor piston in response tomovement of the motor piston into the limits of its return and workingstrokes, respectively. In accordance with my earlier invention, I e needfor such a pilot valve control was obviated by the provision of areversing valve in which the valve member was seatable and unseatable inresponse to reciprocation of a piston having fluid connections with themotor cylinder. These connections were so arranged that the valve pistonwas movable in opposite directions to unseat and permit seating of thevalve member in response to movement of the motor piston into the limitsof its Working and return strokes, respectively.

Intermediate these limits of motor piston movement, however, the fluidconnections were operable to prevent communication between the valvepiston and working side of the motor piston. Inorder to prevent thesystem from getting on dead center, the valve piston was provided with aspring-pressed actuator or plunger tor maintaining the valve memberunseated during the initial stage of return movement of the piston. Thevalve of my earlier invention also included a spring for retracting thepiston to insure seating of the valve member during the initial stage ofworking movement of the piston. Although this motor enjoyed considerablecommercial success, I did encounter some difiiculty with breakage of theaforementioned actuator spring, particularly since it was ofconsiderable length and relatively small diameter.

An object of this invention is to provide a reversing valve for asingle-acting and essentially automatic =hydrau'lic motor of the generaltype above-described which does not include parts, such as the actuatingspring of my earlier invention, which are susceptible of breakage andother maintenance problems.

Another object is to provide a reversing valve for a motor of thegeneral type above described having means tor retract-ing the valvepiston with a greater force than the spring of my earlier inventionwhile, at the same time, being more compact.

Similarly to the system of my earlier invention, a system employing thereversing valve of the present invention includes a motor cylinderhaving a piston reciprocable therein and a conduit connected to thecylinder for admitting hydraulic fluid to one side of the piston formoving it in a working direction to a first extreme Patented June 11,1963 ice position. The opposite side of the motor piston is continuouslyvented and means including the reversing valve movable to an openposition are provided for exhausting said hydraulic fluid from said oneside of the piston to permit its movement in an opposite direction to asecond extreme position. More particularly, the valve comprises a bodyhaving a passageway therein connecting with the conduit and an outletfrom the body, and a valve member sea-table upon a valve seat disposedacross the passageway intermediate its connection with the conduit andoutlet so that said valve member closes the passageway when seated.

This system also includes pressure responsive means movable upon theadmission of hydraulic fluid thereto in one direction to unseat thevalve member and conduit means connecting the motor cylinder at spacedapart levels therein with the pressure responsive means. Valve means inthe conduit means are automatically operable in the first extremeposition of the piston to admit said hydraulic fluid from said cylinderon said one side of the piston and through one of said connections tothe pressure responsive means and, in .the second extreme position ofthe piston, to exhaust said hydraulic fiuid from said pressureresponsive means and through said other connection into the cylinder onsaid other side of the piston. Means to be described more fullyhereinafter are provided for urging the pressure responsive means in anopposite direction so that the valve member may seat upon the exhaustionof hydraulic fluid from said pressure responsive means.

This valve means is operable during movement of the piston between saidextreme positions to prevent communication through said conduit meansbetween said pressure responsive means and said one side of the piston.As previously mentioned, it is the initial stage of this movement of thepiston from the first toward the second extreme position which iscritical. This system also includes additional means automaticallyoperable to admit hydraulic fluid from the cylinder on said one side orthe piston to said pressure responsive means during at least thecritical stage of motor piston movement when communication through saidconduit means between said cylinder on said one side of the piston andsaid pressure responsive means is prevented.

This additional automatically operable means comprises additionalconduit means for communicating the pressure responsive means with themotor cylinder at a level nearer the second extreme position of themotor piston than said one connection, and a second valve member adaptedto open said additional conduit means in response to movement of thepressure responsive means in 'a direction to open the first valve memberand to close such communication in response to movement of the pressureresponsive member in the opposite direction. Thus, as the motor pistonmoves into its first extreme position and starts back on its returnstroke, the force upon the pressure responsive means due to thehydraulic fluid admitted through the additional conduit means will movesaid pressure responsive means to :a position to maintain the reversingvalve member unseated. On the other hand, as the motor piston moves intoits second extreme position and starts back on its working stroke, theclosing of the second valve member will prevent the application of sucha force to the pressure responsive means and thereby avoid prematureopening of the reversing valve member.

In accordance with the present invention, the second valve member aswell as the pressure responsive means are contained within the body ofthe reversing valve. For this purpose, the body also includes a cylinderoffset from the passageway connecting the conduit for admittinghydraulic fluid to the cylinder and an outlet from the body. Ports areprovided in the cylinder for connection 3 with the conduit means andadditional conduit means, and a valve seat for the second valve memberis disposed intermediate the cylinder and the port which is connectableto the additional conduit means. The pressure responsive means of thevalve comprises a piston reciproca bly mounted in the cylinder andextending between said valve members to provide a force transmittingconnection operable to unseat the first valve member when the piston isurged in one direction by the admission of hydraulic fluid to saidcylinder and to seat the second valve member when the piston moves inthe opposite direction upon the exhaustion of hydraulic fluid from saidcylinder.

In accordance with another novel aspect of the present invention, thepiston of the reversing valve may be provided with a surface forming apart of a pressure chamber within the cylinder and so arranged as tourge the piston in a direction to permit seating of the first valvemember upon the admission of pressure fluid to the chamber and theexhaustion of hydraulic fluid from the opposite side of the piston. Moreparticularly, this chamber is connected with the passageway in the valvebody so that the piston is retracted by the force of hydraulic fluidacting upon said piston surface.

It is important that the two valve members of the reversing valve areseated substantially simultaneously, because if there is too much lagbetween their seating, the system may get on dead center, as will beapparent from the description to follow. Even when the valve members areproperly installed, only a small amount of slack or wear of the partstherebetween is suflicient to cause relatively large lag between theirseating.

Therefore, it is a more particular object to provide a reversing valveof the general character defined which may be easily and quicklyadjusted in such a manner as to insure the substantially simultaneousseating of both valve members.

For this purpose, means are provided for changing the effective lengthof the force transmitting connection between the valve members. This maybe accomplished either by adjusting the position of at least one of saidseats with respect to the other seat or by adjusting the length of thepiston. In a preferred form, the passageway and cylinder in the valvebody are substantially axially aligned, and one of the valve seats isformed on an axially movable bushing to permit the aforementionedadjustment. The valve member seatable on the other seat may bereleasably located in seated position by means of an axially movablestem so as to facilitate the aforementioned adjustment.

It is desirable to gradually decelerate movement of the motor pistontoward the end of its return stroke so as to reduce shock loads on thesystem. When the motor is used to reciprocate a sucker rod for adown-the-well pump, debris will often accumulate below the valves of thepump, and it is necessary to bump bottom with the pump in order to shakethis debris loose.

A further object of this invention is to provide a system which isadjustable in a manner to perform both of these functions.

This latter object is accomplished by means of a sys tem of the generaltype described which includes an adjustable choke in the conduit meansintermediate the pressure responsive means and the other connection ofsaid conduit means into the motor cylinder. Thus, this choke controlsthe rate at which hydraulic fluid is exhausted from the pressureresponsive means so that, if it is desired to bump bottom, the choke isclosed down to substantially restrict exhaust through the conduit means.On the other hand, the choke may be adjusted to cushion the returnmovement of the motor piston to any desired degree.

Other objects, advantages and features of this invention will beapparent to one skilled in the art upon a consideration of the writtenspecification, attached claims and the annexed drawings.

In the drawings wherein like reference characters are used throughout todesignate like parts:

FIGURE 1 is a schematic sectional view of the motor of the hydraulicsystem employing the reversing valve of this invention during anintermediate portion of the working stroke of the motor piston;

FIGURE 2 is a view similar to FIGURE 1 but with the motor piston at oneextreme position or limit of its working stroke;

FIGURE 3 is another similar view of the motor during an intermediateportion of the return stroke of the motor piston;

FIGURE 4 is a view similar to FIGURE 3, but in which the motor pistonhas descended still further in its return stroke;

FIGURE 5 is a further similar view with the motor piston at its otherextreme position or limit of its return stroke;

FIGURE 6 is an enlarged sectional view of one embodiment of thereversing valve of the motor of FIG- URES 1-5, with both valve membersin seated position;

FIGURE 7 is a cross-sectional view of the valve of FiGURE 6, takensubstantially along broken line 7--7 thereof;

FIGURE 8 is an enlarged sectional view of another embodiment of areversing valve constructed in accordance with the present invention,with both valve members in unseated position; and

FIGURE 9 is a cross-sectional view of the valve of FIGURE 8, takensubstantially along broken line 99.

Referring first to the schematic views of FIGURES 1-5, the motorincludes a motor cylinder 20 which is closed at its upper end 21, apiston 22 reciprocable in the motor cylinder, and a rod 23 on the pistonextending through the lower end 24 of the cylinder. In accordance with apreferred usage of the motor, the rod may be a polish rod for connectionwith a down-thewell pump, in a manner well known in the art. The pistonis moved in a working or upwardly direction by means of hydraulic fluidsupplied to the working or lower side 25 thereof through a conduit 26connected to the lower end of the cylinder 20. The conduit 26 may beconnected with a suitable reservoir (not shown) of hydraulic fluid underpressure. The lower end of the cylinder is provided with a reduceddiameter portion having an upwardly facing shoulder 27 which preventsmovement of the piston 22 over the connection of conduit .26 with theinterior of the cylinder. The opposite or upper end 28 of the motorpiston 22 is continuously vented by means of a conduit 30 connecting theupper end of the cylinder with any suitable source at a pressuresubstantially less than that of the hydraulic fluid and similar to thatto which such fluid is exhausted from the working side 25 of the motorpiston, in a manner to be described hereinafter.

The reversing valve '31 includes a body 32 having a passageway 33therein connecting with the conduit 26 and an outlet 34 therefrom. Avalve member 35 is seatable upon a valve seat 36 disposed across thepassageway 33 intermediate its connection with conduit 26 and outlet '34so as to close the passageway. When the valve member 35 is seated, asshown in FIGURES 1 and 5, hydraulic fluid conducted through conduit 26will be admitted to the cylinder on the lower side 25 of the piston 22so as to move the piston in a working direction. However, when the valvemember is unseated, in a manner to be described below, the hydraulicfluid on the lower side of the motor piston will be exhausted from thecylinder and through the conduit 26 and passageway 33 into the outlet-34. As previously mentioned, it is contemplated by the presentinvention that conduit 30 and outlet 34 will connect at their outer ends(not shown) with sources having the same, or at least substantially thesame, pressure. For example, in a continuous pumping system of thistype, each of the conduit 30 and outlet 34 may connect with the upperend of a hydraulic fluid reservoir (such as that connecting with conduit26) which may be at an atmospheric pressure. In such a case, conduit 30may connect with the portion of the passageway '33 in the valve body 32beneath seat 36 and opposite the outlet 34, as shown in FIGURE 6.

The valve 31 is also provided with pressure responsive means in a formof a cylinder 37 in the body 32 thereof and a piston 38 in the cylinderwhich is movable upon the admission of hydraulic fluid to the lower side39 thereof in a direction to unseat the valve member 35. Each of a pairof conduits 40 and 41 is connected to the motor cylinder at one of twospaced apart levels and both conduits have a common connection through aconduit 42 with the valve cylinder beneath the valve piston 38. Disposedwithin conduit 40 is a check valve 43 automatically operable, uponmovement of the piston to the extreme position of FIGURE 2, to admithydraulic fluid from the cylinder beneath the motor piston 22 to thevalve cylinder 37 beneath the valve piston. This check valve 43 maycomprise any suitable construction, such as is shown schematically inFIGURES 15, which is urged to an open position by fluid pressure in theend of the conduit 40 connecting with the cylinder 20. A check valve 44within conduit 41 is automatically operable, upon movement of the motorsystem to the limit of its return stroke (FIGURE 5), to exhaust thehydraulic fluid from beneath the valve piston 38 through conduits 42.and 41 into the motor cylinder 20 on the side 28 of the motor piston.More particularly, the check valve 44 is of suit able construction whichis urged to a closed position by means of fluid pressure in the end ofconduit 41 connecting with the motor cylinder.

The valve member 35 comprises a ball and the piston 33 is provided withan actuator 45 which extends through an opening 46 connecting passageway33 and cylinder 37 of the body so that when the piston is moved upwardlyby the admission of hydraulic fluid to the valve cylinder beneath piston38, the upper end of the actuator forces the ball oil of its seat. Acoil spring is disposed about the actuator between the cylinder and thepiston 3-8 to urge the latter in a downward direction. Thus, upon theexhaustion of hydraulic fluid from beneath the piston 38, the valvepiston will be retracted so as to permit the valve member 35 to seat. Ina manner to be described more fully hereinafter, the coil spring 47 maybe replaced by other suitable means, such as fluid pressure, for urgingthe valve piston in a direction to permit seating the valve member 35.

Obviously, the valve is so designed that, in the FIG- URE 4 position ofthe motor, the combined force on the valve member 35 and in the spring47 will be sufficient to retract the valve piston, while, in the FIGURE2 position thereof, the force due to hydraulic fluid acting upon theside 39 of the piston will be sufli-cient to overcome the force in thespring and on the valve member so as to move the piston upwardly.

It will be understood that as the motor piston 22 begins to movedownwardly from its extreme position of FIG. 2, it will cover theconnection of conduit 44} with the cyiin der 20 and thereby preventcommunication through the conduit t2 between said cylinder beneath themotor piston and the valve cylinder 37 beneath the valve piston '38. Ifit were not for the novel apparatus to be described including parts ofthe valve 31, and this return movement of the motor piston were so fastthat the Valve member 35 was barely lifted from its seat, this shuttingoil of hydraulic fluid from the bottom ct piston 38 might cause thevalve member 35 to seat prematurely and the system to get on dead centerwherein the motor piston would reciprocate in short, incomplete strokes.

This apparatus comprises a conduit '48 connecting the valve cylinder 37beneath the piston 38 with the conduit 41 intermediate the check valve44 and the connection of said conduit 41 with the motor cylinder 20, anda valve member 49 seatable upon the connection of conduit 4-8 with thecylinder 37 to open said conduit in response to movement of the piston38 in an upward direction to unseat the valve member '35 and to closesaid conduit in response to downward movement of the piston. Thus, evenas the motor piston 22 moves downwardly from its FIG. 2 position overthe connection of conduit 40* with the cylinder 20, the valve piston 38will be moved upwardly into its position tully unseating valve member 35by the admission of hydraulic fluid to the bottom of said valve pistonthrough the conduits 41 and 48 and past valve member 49". On the otherhand, even as the motor piston 22 moves upwardly from its FIG. 5position over the connection of conduit 41 with the motor cylinder 20,the valve member 35, which has seated due to the exhaustion of hydraulicfluid from beneath the valve piston 38, will not be prematurely unseatedby means of hydraulic fluid flowing into the cylinder 37 through conduit48 because the conduit 48 has been closed by the valve member 49.

The valve member 49 also comprises a ball, the upper end of which isengaged by the lower side 39 of the valve piston 38 as the latter movesdownwardly to permit seating of the valve member 35. Obviously, however,both valve members may take other forms. For example, the valve member49 may be integral with the piston 38. Also, if desired, both valvemembers may be of a sleeve type cooperable with ports in the valve body.

As previously mentioned, it is important that both valve members 35 and49 are seated substantially simultaneously. That is, if, upon movementof the motor piston into the FIG. 5 position, the valve member 49 doesnot seat substantially simultaneously with the valve member 35, themotor piston may rise above the connection of conduit 411 with the motorcylinder prior to seating of the valve member 49. As a result, the valvepiston 38 may be raised and the valve member 35 unseated prematurely.

Theoretically, in order for the valve members 35 and 49 to seatsimultaneously, the piston 38 and actuator must provide aforce-transmitting connection equal in length to the distance betweenthe seated positions of the valve members. This adjustment of the valveparts may be made, either upon the installation of the system or afterwear upon the parts, by means which, in the reversing valve 31 of FIGS.6 and 7, comprises a bushing 50 threadedly received in the lower end ofthe valve body for movement axially of the cylinder 37 and passageway 33and having the seat for valve member 49 formed thereon. The bushing 50is provided with a threaded socket 51 for receiving the conduit 48, anda passageway 52 therethrough connecting the socket and cylinder 37 toform a continuation of the conduit 48. Thus, the bushing may be movedinwardly or outwardly, 'as desired, to bring the piston 38 and itsactuator 45 into engagement at its opposite ends with the seated valvemembers 35 and 4-9. An O-ring 53 surrounds the bushing to seal with theremainder of the body, and a nut 53a on an outer threaded portion of thebushing permits it to be locked in adjusted position.

The motor piston descends at a rate which is determined by the rate offlow past the unseated valve member 35. This rate of flow is, in turn,controlled by means of a stem 54 threadedly received in the opposite endof the valve body for extension axially of the passageway 33. This sternmay be adjusted so as to determine the extent of movement of the valvemember 35 oif of its seat 36, and thus the rate of flow past such seat.This adjustable stem 54 also aids an operator in feeling the movement ofactuator 45 into engagement with valve member 35 during manipulation ofbushing 50. Obviously, after the adjustment has been made, the stern maybe retracted into a position limiting unseating movement of valve member35 to a desired amount. The stem is sealed with respect to the remainderof the body by an O-ring 54a and may be locked in either valve memberlocking or limiting position by means of a nut 54b.

The valve seat 36 is also formed on a separate bushing 55 having anO-ring 56 thereabout for sealing with the passageway 33. Moreparticularly, both valve seats are formed on countersunk portions oftheir respective bushings to guide them during seating and unseating.The lower end of stem 54 and a short stem 57 on the piston face 39prevent the escape of the valve members 35 and 49, respectively, whensuch valve members are unseated.

The upper and lower ends 58 and 59 of the valve body are removable topermit the assembly and replacement of the various parts of the valve.Coil spring 47 is held between an annular shoulder 68 at the upper endof cylinder 37 and an annular surface on the top of piston 38surrounding actuator 45. An enlarged diameter portion of the piston isprovided with seal rings 61 thercabout for sealably sliding within anenlarged diameter portion of the cylinder 37. An annular shoulder 62 atthe top of this last-mentioned cylinder portion provides a stop toupward movement of the piston 38.

The embodiment of reversing valve shown in FIGS. 8 and 9 is, in manyrespects, similar to that above'clescribed in connection with FIGS. 6and 7. Thus, as shown in FIGURES 8 and 9, this valve 6'3 comprises avalve body 64 having a passageway 65 therein provided with ports forconnection with the conduit 26. A valve seat 66 is disposed across thepassageway intermediate its intersection with conduit 26 and an outlet34 therefrom so that a ball valve member 67 is seatable thereon to closethe passageway. Also, the valve body is provided with a cylinder 68therein substantially axially aligned with the passageway 65, and portsin the cylinder for connection with conduits 42 and 48 below the lowerside 69 of a piston 70 reciprocable within the cylinder.

As in the case of the previously described embodiment, the valve body 64has an opening 71 therethrough connecting its passageway and cylinder,and the piston 70 has an actuator 72 extending through said opening forengagement at its upper end with the ball valve member 67. Thus, uponthe admission of hydraulic fluid to the valve cylinder 68 beneath thepiston 70, the piston and actuator 72 will be moved upwardly so as tounseat the valve member 67. On the other hand, upon the exhaustion ofhydraulic fluid from beneath the piston 70, the piston will movedownwardly to permit seating of the valve member 67 As distinguishedfrom the previously described embodiment, however, the piston 70 of thevalve 63 is urged downwardly by pressure responsive means which iscapable of providing a larger retracting force and which takes up lessspace than the coil spring 47 of said other embodiment. Thus, the body64 of the valve is provided with one or more ports 73 therethrough(shown rotated in FIG. 8) for connecting the passageway 65 above seat 66with an annular chamber in the cylinder 68 formed on opposite sidesbetween the actuator 72 of the piston and the valve cylinder and sealedbelow by seal rings 75 about an enlarged diameter of the piston 70 andabove by a seal ring 74 carried by the body in the opening 71 forsealing about the actuator 72. It will be understood that the pressureof the hydraulic fluid in the passageway 65 above the seat 66 will urgethe piston 70 downwardly.

Although this pressure responsive retracting means may be preferred overthe coil spring of the FIGURES 6 and 7 embodiment for the reasonspreviously noted, there are some auxiliary advantages of a coil springwhich may make it desirable to use same in conjunction with the pressureresponsive retracting means. For example, a coil spring arranged asshown in FIGURE 6 will compensate for a certain amount of slack in thesystem by forcing the lower valve member to a seated position upon aprior seating of the upper valve member. A coil spring is also useful inprepositioning the valve piston when starting the system.

The seal rings 75 on the piston 70 are spaced apart and the piston andits actuator 72 are ported at 76 to connect the portion of thepassageway 65 intermediate seat 66 and seal ring 74 with an annularspace about the piston between the rings 75. Inasmuch as the fluid inthis portion of the passageway is substantially atmospheris, or lessthan system pressure, it prevents leakage from the annular chamber abovethe topmost ring into the cylinder beneath the piston 70.

As in the case of the previously described embodiment, the bottom 69 ofthe piston 70 is engageable with a valve member 77 so as to move it intoseated position upon the seat formed at the intersection of conduit 48with the cylinder 68. In this embodiment of the invention, the seat forvalve member 77 is formed upon the removable lower end 78 of the body,and the adjustment for insuring substantially simultaneously seating ofthe valve members 66 and 67 comprises an axially adjustable stem 79 onthe lower end 69 of the piston. As in the case of the adjustable bushing50 of the valve embodiment of FIG- URES 6 and 7, this valve alsoincludes an adjustable stem 80 for limiting the extent to which thevalve member 67 may be unseated and thus controlling the rate of flowpast the seat 66.

Referring again to FIGURES 1-5, the adjustable choke 81 is showndisposed within conduit 41 intermediate the connection of said conduitwith motor cylinder 20 and the conduit 48. As previously described, thischoke is adjustable to cushion the descent of the motor piston to adesired extent. At the same time, it cushions the rise of the piston ina manner obvious from the drawings. If the adjustable choke 81 is alsoto be used in bumping bottom, the down-the-well pump is so supportedfrom the rod as to be spaced just a few inches above the bottom of thewell. Thus, the pump will be caused to bump bottom, for the purposesabove-described, upon closing down of the choke.

Reviewing now the overall operation of the system, particularly withrespect to the reversing valve 31, it will be understood that with thepump for the hydraulic fluid shut off, the locating stem 54 may be movedinwardly to seat the valve member 35 on its seat and the bushing 50moved inwardly to force the upper end of the actuator 45 against thebottom side of the valve member 35. The locating stem may then beretracted to permit a desired amount of travel for the valve member 35.

At this time, both the motor piston and valve piston are in the loweredpositions of FIGURE 5 and the valve members 35 and 49 are seated. As thepump is started, hydraulic fluid is admitted to the cylinder 20 beneaththe motor piston to move it upwardly past the connection of conduit 41with the motor cylinder. However, the check valve 44 is efiective toprevent hydraulic fluid beneath the motor piston from admission to thelower side 39 of the valve piston through the conduit 42. Since the areaacross seat 36 is greater than that across the seat for valve member 49,it is obvious that the force due to system fluid acting upon valvemember 35 plus the force of spring 47 is greater than the force due tosuch fluid acting upon valve member 49 so that the valve piston remainsin its lower position to maintain the valve member 49 seated despite thefact that hydraulic fluid is conducted through the conduit 48 beneaththe piston to the lower side of the valve member 49.

When, however, the motor piston moves upwardly past the connection ofconduit 40 with the motor cylinder (FIGURE 2), the check valve 43 iseffective to permit hydraulic fluid to be admitted through conduit 42 tothe lower side of the valve piston 38. Since the force due to systemfluid acting upon the surface 39 of piston 38 is greater than that dueto the spring 47 and the fluid at reduced pressure on the oppositesurface of the piston, the valve piston is raised so as to unseat thevalve member 35 and thereby permit exhaustion of hydraulic fluid frombeneath the motor piston through the outlet 34. At the same time, thismovement of the valve piston permits the valve member 49 to unseat dueto the influence of hydraulic fluid acting upon its lower side. Thus,even though the motor piston might drop quickly past the connection ofconduit 40 with the motor cylinder, the force upon the lower side of thepiston due to the admission of hydraulic fluid through the conduit 48will insure sufiicient travel of the valve member 35 in an unseatingdirection so as to prevent the system from getting on dead center.

To explain further, as soon as the motor piston 22 moves above theintersection of conduit 40 with the motor cylinder, the system fluidwill be admitted to the pressure responsive surface 39 of piston 38 ofthe reversing valve so as to unseat ball valve member 35. As the ballvalve member is unseated, system fluid will be vented from beneath themotor piston through the outlet 34. If the upwardly directed force uponthe piston of the reversing valve is not sufiicient to fully unseat theball 35, there may be a pressure drop across the restriction between theball and its seat which, together with venting of system fluid throughthe outlet 34, may be suflicient to draw the ball back down onto itsseat. On the other hand, even if the ball valve member 35 is notprematurely seated, if it is not fully unseated, the motor piston willnot move downwardly at the intended speed. It is to avoid theseshortcomings that motors of this type have hereto-fore included a pilotvalve control of the type previously described.

This last mentioned force is effective during the travel of the motorpiston downwardly to a position in which it covers the connection ofconduit 41 with the motor cylinder. As the motor piston drops furtherpast this last-mentioned connection, the check valve 44 is efiective topermit hydraulic fluid to be exhausted from beneath the valve pistonthrough the conduit 42. As a result, intermediate the positions FIGURES4 and 5, the valve piston will be lowered to permit seating of the valvemember 35. Thus, hydraulic fluid conducted through conduit 2 6 willagain be directed to the working side of the motor piston so that it isagain urged in an upwardly or working direction. This exhaustion ofhydraulic fluid from beneath the valve piston and the resulting downwardmovement of such piston also causes the valve member 49 to be seated. Inthis way, even though the motor piston might start back upwardly at afast rate, the valve member 49 will be seated prior to the uncovering ofthe connection of conduit 41 with the motor piston upon upward movementof the motor piston.

From the foregoing it will be seen that this invention is one welladapted to attain all of the ends and objects hereinab-ove set forth,together with other advantages which are obvious and which are inherentto the apparatus.

It will be understood that certain features and subcombinations are ofutility and may be employed without reference to other features andsnbco-rnbinations. This is contemplated by and is within the scope ofthe claims.

As many possible embodiments may be made of the invention withoutdeparting from the scope thereof, it is to be understood that all matterherein set forth or shown in the accompanying drawings is to beinterpreted as illustrative and not in a limiting sense.

The invention having been described, what is claimed 1s:

1. A valve, comprising a body having a passageway therethrough and acylinder therein, an inlet to and outlet from the passageway, a firstvalve member seatable on a first valve seat intermediate the inlet andoutlet to close the passageway, a port in the cylinder, a second valvemember within the cylinder seatable on a second valve seat at theintersection of the port with said cylinder, a piston having an actuatorat one end extending into the passageway and between said valve membersand 'sealalbly slidable within the cylinder in one longitudinaldirection to unseat the first valve member and permit unseating of thesecond valve member and in an opposite longitudinal direction to seatthe second valve member and permit seating of the first valve member,and means for selectively holding the first valve member upon the firstseat and adjusting the longitudinal distance between the second valveseat and the outer end of the actuator, whereby the valve members andpiston may be brought into engagement with one another when said valvemembers are seated.

2. A valve of the character defined in claim 1, wherein said meanscomprises means for moving said second seat longitudinally of thecylinder.

3. A valve of the character defined in claim 2, wherein said meansincludes a stem movable longitudinally of the passageway for limitingthe extent to which said first valve member may be moved in an unseatingdirection.

4. A valve of the character defined in claim 1, wherein said meanscomprises means for extending and retracting the length of the piston.

5. A valve of the character defined in claim 4, wherein said meansincludes a stem movable longitudinally of the passageway for limitingthe extent to which said first valve member may be moved in an unseatingdirection.

6. A valve of the character defined in claim 1, including means in saidbody urging said piston and actuator in said opposite direction.

7. A valve of the character defined in claim 1, wherein said port isadapted to admit fluid to one side of the piston to move it in said onedirection, and including means forming an enclosed chamber on theopposite side of the piston, and a conduit connecting said chamber withthe passageway intermediate the first valve seat and inlet for admittingfluid from said passageway to said opposite side of the piston to urgeit in said other direction.

References Cited in the file of this patent UNITED STATES PATENTS1,381,765 Thompson June 14, 1921 1,540,181 Olson June 2, 1925 1,878,356Wilcox Sept. 20, 1932 2,084,707 Robinson June 22, 1937 2,240,791Leeseberg May 6, 1941 2,342,001 Magnuson Feb. 15, 1944 2,630,828 BentMar. 10, 1953 2,648,346 Deardorfi Aug. 11, 1953 2,685,892 Edwards Aug.10, 1954 2,738,806 Reynolds Mar. 20, 1956

1. A VALVE, COMPRISING A BODY HAVING A PASSAGEWAY THERETHROUGH AND ACYLINDER THEREIN, AN INLET TO AND OUTLET FROM THE PASSAGEWAY, A FIRSTVALVE MEMBER SEATABLE ON A FIRST VALVE SEAT INTERMEDIATE THE INLET ANDOUTLET TO CLOSE THE PASSAGEWAY, A PORT IN THE CYLINDER, A SECOND VALVEMEMBER WITHIN THE CYLINDER SEATABLE ON A SECOND VALVE SEAT AT THEINTERSECTION OF THE PORT WITH SAID CYLINDER, A PISTON HAVING AN ACTUATORAT ONE END EXTENDING INTO THE PASSAGEWAY AND BETWEEN SAID VALVE MEMBERSAND SEALABLY SLIDABLE WITHIN THE CYLINDER IN ONE LONGITUDINAL DIRECTIONTO UNSEAT THE FIRST VALVE MEMBER AND PERMIT UNSEATING OF THE SECONDVALVE MEMBER AND IN AN OPPOSITE LONGITUDINAL DIRECTION TO SEAT THESECOND VALVE MEMBER AND PERMIT SEATING OF THE FIRST VALVE MEMBER, ANDMEANS FOR SELECTIVELY HOLDING THE FIRST VALVE MEMBER UPON THE FIRST SEATAND ADJUSTING THE LONGITUDINAL DISTANCE BETWEEN THE SECOND VALVE SEATAND THE OUTER END OF THE ACTUATOR, WHEREBY THE VALVE MEMBERS AND PISTONMAY BE BROUGHT